Excitation of electrolytic condensers



Dec. 19, 1922. I k R. D. MERSHON.

EXCITATION or EL ECTROLY FILED SEPT. I4

TIC CONDENSERS.

.1920. 4 SHEETS-SHEET 1.

I V |NVENT0R- Mi I m f Dec. 19, 1922. 1,439,525. I R. D. MERSHON.

EXCITATION 0F ELECTROLYTIC CONDENSERS.

FILED SEPT-14, 1920. 4 SHEETSSHEET z.

I'BY" INVENTOR monnevs Dec. 19, 1922. 7 1,439,525.

T R. D. MERSHON. T

EXCITATION 0F ELECTROLYTIC CONDENSERS.

FILED SEPT. I'M 1920. I 4 SHEETS-SHEET 3.

I Z2 23 2a; 25

a INVENTOR MQM ATTORNEYS Dec. 19, 1922. 1,439,525.

R. D. MERSHON. J

EXGITATION 0F ELECTROLYTIC CONDENSERS.

FILED SEPT- 14, 1920. I 4 SHEETS-SHEET 4- 2; 5 INVENTOR A roams Patented Dec. 19, 1922.

UNITED STATES PATENT OFFICE.

RALPH D. MERSI-ION, OF NEW YORK, N. Y.

EXCITATION OF ELECTROLYTIC CONDENSERS.

App1ication filed September 14, 1920.

To all whomit may concern.

Be it known that I. RALPH D. MrmsHoN, a citizen of the United States of America,

residing at New York, in the county and State of New York, have invented certain new and useful Improvements in Excitation of Electrolytic Condensers, of which the following is a full. clear, and exact description.

It is now well understood that the functioning of an electrolytic condenser depends (among other things) upon the presence of a negative charge in the electrolyte, the value of which charge is proportional, in general,

to the capacity of the condenser and to the maximum value of the E. M. F. between the condenser terminals. If for any reason this charge is diminished it will be restored by the alternatingcurrent impressed upon the apparatus. This restoration is accompanied by a breaking down of the dielectric films on the electrodes, and if repeated often enough causes serious deterioration of the films with resulting decrease in the efficiency of the condenser. On the other hand, if the charge be maintained from some other source which does not involve flow of current from the electrolyte to the electrodes, as for example by unidirectional current delivered to the. electrodes and led out by way of an unfilmed electrode or terminal immersed in the electrolyte, the aforesaid cause of impairment of the electrode films will be eliminated. Stated otherwise, the condenser tends to operate as a rectifier, producing a unidirectional E. M. F. with a tendency for current to flow from the electrolyte to the electrodes. If this E. M. F. be opposed by a unidirectional E. l d. F. of higher value from an independent source the condenser cannot act as a. rectifier and the constant charge. which the condenser must have to enable it to operate as a condenser. will be supplied and maintained by the independent source.

Prior to the invention described in my copending application Serial No. 181,430, it was considered necessary to provide a separate source of unidirectional current for each condenser, a condition which, as will be readily understood, imposes a limitation upon the use of electrolytic condensers that under some circumstances -may be serious.

' .The invention mentioned provides a system in which the same source of unidirectional current can be used with two or more condensers in series or in multiple or in seriesmultiple, and in my said application I have Serial No. 410,343.

illustrated the invention as embodied in the i preferred manner in systems of condensers arranged for use in series on single phase or polyphase circuits. My present invention relates to the method of exciting a plurality of condensers from a single source, as distinguished from the apparatus, and it relates more specifically to condensers in polyphase circuits.

Referring to the annexed drawings,

Figs. 1 and 2 are diagrams illustratingthe operation of the electrolytic condenser, and a method of exciting the same.

Fig. 3 is a diagram illustrating the application of the invention to condensers in a two-phase three-wire system.

Figs. 4 and5 are diagrams illustrating the excitation of condensers in series by means of a single source of unidirectional current.

Fig; 6 shows a method in which choke coils are used.

Fig. 7 illustrates an arrangement similar to F ig 3, but with a plurality of condensers 1n serles in each circuit of the two-phase three-wire system.

Fig. 8 illustrates another application of Fig. 1. In this figure, A, A, designate electrodes or plates of aluminum or other suittable metal each coated with the necessary dielectric film produced preferably by the methodv described in my prior Patent No. 1,012,889), immersed in a suitable electrolyte, say a solution of borax and boric acid in a vessel or tank B. G' is an electrode composed of a material, for example carbon or nickel, which is incapable of forming a dielectric film such as the plates A are coated With; For this reason C is convenientlyreferred to as a non-filming electrode or cathode, the active electrodes A, A, being cell, as in Fig. 1.

termed anodes. It is connected to a terminal D. E is an autotransformer connected to the condenser terminals F, F', and having its middle or neutral point connected to a terminal G. r Y

Imagine, now, that alternating current is impressed on the condenser terminals and that a positive impulse is coming in over the right hand terminal F. The film on the right hand electrode A. prevents flow of current from the latter to the electrolyte and thence to the non-filming electrode or cathode C; but since the film offers no, or but little, opposition to the flow of current from C to A, there will'be a tendency for current to flow through the autotransformer to G and thence to .D, and it will be readily seen that a like tendency exists when a negative impulse comes in over the left hand terminal F. In short, there exists between G and D a unidirectional E. M. F. If the circuit be closed from G to D, for example through a resistance, the unidirectional current and E. M. F. of open circuit will be of nearly constant value.

Suppose, now, that we insert between G and D a source of unidirectional E. M. F. of opposite direction, as for example the source H, Fig. 2, so as to oppose the potential normally existing between G and D. If the E. M. F. of the source H be less than the maximum unidirectional voltage produced by the alternating E. M. F. on the condenser terminals the condenser will operate as a rectifier and will charge the battery. If the E. M. F. of the battery be just equal to the other no current will flow from or to the battery unless the negative charge leaks away from the electrolyte; in which case current will flow from the battery in sufficient amount to replace the charge or part of the charge so lost, thus avoiding the injury to the films, on plates A, that otherwise would occur by replacement of the charge from the alternating current impressed upon the condenser terminals F, F. However, in order to .certainly insure the desired result the E. M. F. of the battery (or other D. C. source) should be in excess of themaximum unidirectional E. M. F. produced between G and D by.

the alternating E. M. F.

' In the arrangement shown in Fig. 3, each cell contains afilmed electrode or anode, A, and one nonfilming electrode or cathode, C. There are thus twd cells foreach condenser, and the four cells of the figure therefore constitute two condensers in series. The vfunction of the cathodes in cells 2 and 3 is to afford electrical connection between the two electrolytes, the effect being then the same as if both anodes A were in one Tn the case of cells 1 and 4 the cathodes afford paths for the condenser or displacement current from the anodes of cells 1 and 4 to the anodes of cells 2 and 3. The theory and operation of the electrolytic condenser in general is exlained at length in my prior Patent No. 1,077,628, issued November 1, 1913, part 1c" ularly in lines 4 to 124 on page 3tl1ereof. Reverting to Fig. 3, the terminals of the autotransformer F are connected to the condenser terminals, and the cathodes C of the inner cells 2, 3, are connected through a unidirectional source H to the neutral point of the transformer. It will readily be seen that the E. M. F., produced by alternating voltage impressed on the condenser tenninals, and tending to cause flow of current from the neutral point of the transformer to the cathodes of the inner cells, is opposed by the opposite E. M. F. of the battery or other source H. Tn the arrangement shown in Fig. t no transformer is needed, but each condenser is divided into four cells instead of two as in Fig. 3. When an impulse of the alternating current comes in at the right hand terminal the lower cells operate as valves, the two at the right offering no opposition to the flow of current and the two at the left opposing it. When an impulse comes in at the left, the lower cells at the left offer no opposition to the current but the two at the right oppose it. Thus a unidirectionalE. M. F. is produced between -cases where choke coils are employed they should be of the open magnetic circuit type so that their cores will not be saturated.

Fig. 6 illustrates an embodiment of my present invention for a two-phase three-wire system, having terminals 10, 11, 12, for connection with the external A. C. circuit, the condensers 13, 14 being connected between the middle terminal 12 and the outside terminals 10, 11, respectively. The cathodes are connected by an autotransformer or balance coil 15, to the neutral point of which is connected the negative -pole-of the unidirectional exciting source 16, .Across the condensers are autotransformers 17, 18, and to the neutral points of the latter the terminals of an autotransformer' 19 are connected. The neutral point of the transformer 19 is connected to the positive pole of the source 16.

From the foregoing it will be seen that the autotransformers 17, 18, 19 not only constitute means for connecting the anodes in multiple to the source 16 of the undirectional exciting current, .so that the exciting current is split up into separate currents and the latter supplied to thefilmed electrodes or anodes, but the autotransformers at the same time, by their inductive or transformer action when alternating current is impressed on the terminals 10, 11, 12, provide counter E. M. Fds opposing any alternating voltages existing between the paths of the split unidirectional current. 'Hence the alternating voltages between the points of multiple connection of the electrodes to the unidirectional source, are not sh'ort-circuited.

in principle the invention comprises feeding the unidirectional exciting current to the condensers at points which are neutral with respect to the alternating currents. Thus the point of connection of the autotransformer 19 to the D. C. source 16 is neutral with respect to the alternating current impressed on the condensers, and the points of connection of the autotransformers 17 and 18 are neutral with respect to the alternating current impressed upon the anodes of the re spective condensers. Similarly, the point of connection of the unidirectional source to the autotransformer 15 is neutral with respect to the electrolytes.

Fig. 6 shows a single condenser in each circuit of the system. If a plurality of condensers are used (in series) in each circuit the method described in my copending application Serial No. 181,430 may be used to take care-0f the series connection, as in Fig. 7. 1n the latter figure are shown two sets of condensers 13, 14, of which the condensers of each set are in series; condensers 13 being in series with each other and condensers 14 being in series with each other, while set 13 and set 14 are each on its own phase. The balance coils 15 15, are connected by their neutral points to the terminals of a balance coil 15" which in :turn is connected by its neutral point to the negative pole of the exciting source 16.

In the modification illustrated in Fig. 8, two single phase autotransformers or balance coils 20, 21 are provided but connected together for twophase operation, and connected to the terminals 10, 11, 12 as shown. The unidirectional exciting source 16 has its negative pole connected to the neutral point of the autotransformer 15 as in Fig. 6, and its positive pole to the corresponding neutral point of the combination of transformers 21 and 20.

Fig. 9 shows the invention applied to a two-phase system having independent circuits, with terminals 22, 23, 24, 25 for the condensers 13, 14. As before, the neutral points of the autotransformers 17 18, are connected to the positive pole of the exciting source 16, and the neutral point of transformer 15 is connected to the negative pole. In'Fig. 10 the condensers 13, 14 are connected to the external circuit (represented by the terminals 22, 23,- 24, 25) through the medium of transformers 26, 27. The neutral points of the secondaries of these transform ers are connected to the positive pole of the exciting source 16 and the negative pole of the latter is connected to the neutral or halfway point between the cathodes C,

The remaining figures illustrate variousways of applying the invention to threephase systems. Fig. 11 shows a delta-connection 'of condensers 28, 29, 30, having their cathodes connected to a star-connectedthreephase autotr'ansformer 31. The neutral point of the latter is connected to the negative pole of the exciting source 16, which has its positive pole connected to the neutral point of a three-phasetransformer 32. The latter is shown as an autotransformer, but it may represent the secondary" of the main three-phase transformer. In speaking of a three-phase transformer or autotransformer I mean to include combinations of transformers or autotransformers connected for three-phase transformation, as for instance three single phase transformers with their primaries in delta, and their secondaries, feeding the condensers, in star. Similarly in the case of quarter phase transformation. The terminals of 32 are connected to the corresponding terminals of the condensers.

'In Fig. 12 the cathodes of the condensers 281, 29, 30 are connected to'the terminals of a pair of single phase autotransformers 33, 34, arranged for three-phase operation. with the three-phaseneutral point of the combination of 33 and 34 connected to the negative pole of the source 16. The positivepole of the latter is similarly connected to a pair of single phase transformers 35, 36. arranged for three-phase operation and having their terminals connected to the corresponding terminals of the condensers. As in the case of transformer 32, Fig. 11, and 36 are shown as autotransformers, but they may represent the secondaries of the main transformers. In Fig. 13 the condensers 28 29 30 are in independent circuits, with autotransformers 37, 38, 39 across the respective condenser terminals 40 41, 4243, 44-45. The exciting current from the source 16 is led to the neutral points of these transformers. The cathodes of condensers 28 and 29 are connected to the terminals of an autotransformer 46, and the neutral point of the latter, and the cathode of condenser 30 are connected to the terminals of an autotransformer 47 whose neutral point is connected ing current is impressed on the system,

choke coils will cut down to some extent the unidirectional voltage impressed on the system. This is one reason why autotransformers are preferable. In most if not all cases where choke coils are employed they should be of the open magnetic circuit type so that their cores will not be saturated.

'Figs. 1 1 and 15 show the invention applied to lightning arresters, in the present instance arresters for a three-phase system. The cells 50, each having one filmed anode A and an unfilmed cathode C, are connected in series of the three phases, two in each, and the neutral point of the three sets is grounded, as indicated at 51. The terminals 52, 53, 54, by which the arrester is connected to the line, are connected to the terminals of a three-phase autotransformer The exciting source 56 is connected between the neutral point of the arrester and the neutral point of the transformer. In 14, in which the. arrester anodes are toward the terminals 52, 53, 54, the positive pole of the exciting source is connected to the trans former, and in Fig. 15, in which the anodes are toward the neutral point of the arrester the negative pole of the source is connected to the transformer, so that in each case flow of current from the electrolyte to the anodes is opposed.

From the foreging the preferred method of connecting the condensers or other electrolytic devices in polyphase circuits with the source of unidirectional current may be briefly summarized as follows: (1) Establish a neutral point among the cathodes; (2) Establish for each condenser a neutral or half-way point among its anodes; (3) Establish a neutral point among the anode half-way points; (4) Feed the excit- -ing current into the system at a neutral point of the half-way points and out at the cathode neutral point.

It is to be understood thatthe invention is not limited to the procedure herein specifically illustrated and described but can be practised in other ways without departure from its spirit.

I claim:

1. The method of exciting a plurality of electrolytic condensers or other electrolytic devices, comprising splitting up current from a single source of unidirectional current and supplying the resulting currents to the several devices through a point neutral to the anodes of the several devices and leading the current out through a point neutral to the cathodes of the same devices, and simultaneously generating electromotive forces in opposition to alternating electromotive forces existing between the paths of the said currents.

2. The, method of exciting a plurality of electrolytic condensers or other electrolytic devices, comprising connecting the anodes of the devices in multiple, supplying the exciting current from a single unidirectional source to the neutral point of the multiple connection of the anodes whereby the exciting current is split up into a plurality of currents, and simultaneously generating electromotive forces in opposition to alternating electromotive forces existing between the paths of the said currents.

3. The method of exciting a plurality of electrolytic condensers or other electrolytic devices, comprising establishing a neutral.

cathodes, and feeding unidirectional cur-.

rent from a slngle source to the first mentioned neutral point and out at the second.

4:. The, method of exciting a plurality of condensers or other electrolytic devices in different phases of a polyphase system, comprising connecting the electrolytes inmultiple across said phases and establishing a neutral point therefor, connecting the anodes in .multiple across said phases establishing a neutral point therefor; feeding unidirectional current from a single source into the second neutral point and out at the first and simultaneously generating electromotive forces in opposition to alternating electromotive forces between the points of multiple connection:

5. The method of exciting a plurality of electrolytic condensers in different phases of a polyphase system, comprising connecting the condenser electrolytes in multiple across said phases and establishing a neutral point therefor, connecting the anodes of each condenser in multiple and establishing a neutral point for each condenser, connecting the RALPH D. MERSTION.

and and its 

